Safety cover lock for the case of an electrically operated device

ABSTRACT

The base and cover portions of a container intended for housing an electrically operated device are provided with latching means effective for securing the cover to the base when the device is in an operating state, and for conveniently removing the cover from the base for maintenance and repair purposes. The latching means cooperates with the electrical supply cord of the housed device in such manner as to require its disconnection therefrom, at its point of entry into the case, before the cover can be removed from the base, and to prevent its reconnection therewith until the latched relationship between the cover and the base is reestablished.

United States Patent Inventor Appl. No. Filed Patented Assignee SAFETY COVER LOCK FOR THE CASE OF AN ELECTRICALLY OPERATED DEVICE 2,540,296 2/ l 951 Schwend et a1 312/208X 3,141,713 7/1964 Kaufiman 339/144X 3,147,056 9/1964 Mendelson 339/36 Primary Examiner-Richard E. Moore Attorneys-Kenneth L. Miller and Frank H. Cullen ABSTRACT: The base and cover portions of a container inclaimssnrawing Figs' tended for housing an electrically operated device are pro- [52] US. Cl 292/45, ided with latching means effective for securing the cover to 292/2l6 the base when the device is in an operating state, and for con- [51] Int. Cl E05c 3/26 v ni nfly removing the cover from the base for maintenance [50] Field of Search 292/216, d repair r o e The latching means cooperates with the (TC), 56; 339/36, 44; U q electrical supply cord of the housed device in such manner as to require its disconnection therefrom, at its point of entry [56] References cued into the case, before the cover can be removed from the base, UNITED STATES PATENTS and to prevent its reconnection therewith until the latched 1,390,773 9/ l 92] Foster 292/216X relationship between the cover and the base is reestablished.

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SAFETY COVER LOCK FOR THE CASE OF AN ELECTRICALLY OPERATED DEVICE BACKGROUND OF THE INVENTION Many well-known electrical and electromechanical devices are of a nature which would be hazardous to repair or to adjust if they were accidentally operated while in an exposed state, such hazards involving injuries from electric shock and lacerations to fingers and hands resulting from electrically powered mechanical movements. To eliminate such hazards, many well-known safeguards have been provided which serve to prevent the electrically powered operation of such' devices during the time the cover or case is removed therefrom. Prominent among such safeguards is the interlock means associated with the service panel of a radio or television set which prevents access to the workings thereof without interrupting the supply of electric current thereto. It is likewise a common practice in calculating and accounting machines to provide electrical switches that are associated with case panels or covers, such switches being conditioned for current flow when the panels or covers are properly installed, and conditioned to interrupt the flow of current when the panels or covers are displaced or removed from the machine.

These well-known safeguards not only add to the cost of manufacturing the device or machine, but their protective purposes are oftentimes too easily negated by a would-be repairman. In the absence of completely reliable safeguards of a current-interrupt nature, efforts have frequently been made, particularly in electromechanical calculating and accounting machines, to shield the more hazardous electrical and mechanical areas against inadvertent injury to the operator or repairman. Such efforts have generally proven to be ineffectual as well as costly, in view of the speculative nature of what constitutes a hazard from the standpoint of the skilled as well as unskilled repairman.

A common characteristic of many calculating and accounting machines is the need of removing various covers or panels for the performance of such operator tasks as the replacement of ribbons or the substitution of type characters. In connection with these tasks, special attention to safeguards is required in view of the relative skills of the average operator.

Quite apart from the above-named hazards, electrical and electromechanical devices are commonly provided with cases which comprise at least a base portion and a cover portion, the various portions of the case being held in an assembled state with sufficient security to discourage tampering by unskilled and unauthorized personnel, while at the same time providing sufficient facility for convenient removal by authorized personnel and skilled repairrnen.

SUMMARY OF THE INVENTION It is accordingly an object of the present invention to provide a reliable means for securing the cover of an electrically operated device to its base portion, such means permitting convenient removal of the cover by repairmen or by other authorized personnel.

Another object of the invention is to provide latching means associated with the cover and base portions of such container, such latching means incorporating a reliable current-interrupt feature which renders the device incapable of electrically powered operation when the cover is removed from the base.

It is a further object of the present invention to provide a simple latching means for use in conjunction with the cover and base of a calculating machine, such latching means being at the same time economical to build and sufficiently foolproof from a safeguarding standpoint to eliminate the need of shielding the various operating areas of the machine against inadvertent and accidental contact by the repairman.

An important aspect of the invention is the use of a pair of bifurcated latching members interiorly disposed along one side of the cover portion of the container housing the electrically operated device, the prongs of each latching member being connected by a transverse rod.

Another aspect of the invention is the use of a pair of webbed receptacles interiorly disposed along the side of the base portion corresponding to the side of the cover comprising the pair of bifurcated members, the webbing of such receptacles providing arcuate paths of travel for the transverse rods of the bifurcated members and providing also offset recesses for lockably housing the transverse rods when the cover portion is tiltably joined with the base portion.

Still another aspect of the invention is the use of a pair of foot members interiorly disposed along the side of the cover portion opposite the side comprising the pair of bifurcated latching members, each of these foot members comprising an inwardly directed stud.

An additional aspect of the invention is the use of a pair of spring-connected cam hooks interiorly and rotatably disposed along the side of the base portion opposite the side comprising the pair of webbed receptacles, each of these cam hooks being joined by stud and slot connection to a slide member having an ofi'set tab portion operably accessible from the exterior of the base and having also an aperture suitable for receiving the female receptacle of an electrical supply cord.

BRIEF DESCRIPTION OF THE DRAWINGS description when read in conjunction with the accompanying drawings, in which:

FIG. 1 is a right side elevation of the case of a calculating machine in which thepreferred embodiment of the invention may be incorporated and wherein the cover portion of the case is shown in its latched position relative to the base thereof;

FIG. 2 is a rear elevation of the case of FIG. 1 showing the cover portion tiltably separated from the base portion and showing also the supply cord aperture of the base in relative disaligned relationship with the aperture of the slide member;

FIG. 3 is an interior view of the front side of the case of FIG. 1 wherein the cover portion is removably separated from the base portion and wherein the bifurcated latching members and the webbed receptacles of the front latching means are shown in vertically aligned relationship;

FIG. 4 is a fragmentary view taken along the line 4-4 of FIG. 3 showing the cover of the case of FIG. 1 in tilted relationship with the base thereof and with one of the bifurcated latching members in insertable relationship with its associated webbed receptacle",

FIG. 5 is an interior view of the front side of the case taken along the line 5-5 of FIG. 1 and showing the bifurcated latching members of the cover portion in locked relationship with their associated webbed receptacles of the base portion;

FIG. 6 is a view taken along the line 6-6 of FIG. 5 showing the transverse rod of one of the bifurcated latching members in engaged relationship with the offset recess of its associated webbed receptacle;

FIG. 7 is an interior view of the rear side of the case of FIG. 1 showing the cover portion in tiltably separated relationship with the base thereof and showing also the details of the rear latching means when in its unlatched state; and

FIG. 8 is an interior view of the rear side of the case taken along the line 8-8 of FIG. 1 and showing the cover portion of the case in latched relationship with the base portion thereof, and showing also the details of the rear latching means when in its latched state.

DETAILED DESCRIPTION OF THE INVENTION The preferred embodiment of the invention is hereinafter described in conjunction with the case of a calculating machine as shown in FIG. I, such case consisting of a base portion 23, and a cover portion 21 which is securely latchable with and conveniently removable from the base 23. An electrical supply cord is connectable to the calculating machine through an aperture 79 formed in the base 23, as shown in most side of the cover as viewed in FIG. 1),

FIG; 2. The latching means of the present invention is so designed as to require disconnection and removal of the supply cord from the aperture 79 before the cover 21 can be removed from the base, and to prevent the reconnection of the supply cord with the calculating machine through the aperture,79 until the cover 21 is latchably secured to the base 23, as will be explained in greater detail in a succeeding paragraph.

The invention is comprised of front latching means illustrated in FIGS. 3, 4, 5 and 6, and of rear latching means illustrated in FIGS. 7 and 8. With reference to FIGS. 3 and 4, the front latching means is comprised of a pair of bifurcated latching members which are interiorly fixed in spacedapart relationship to the front side of the cover 21 (the leftand a pair of associated webbed receptacles 33 interiorly fixed in spacedapart relationship to the front side of the base 23. Each of the bifurcated latching members 25 is attached to a depending projection 29 of the cover 21 by means of a screw 31, and the prongs of each bifurcated member are connected by a transverse rod 27, such prongs being formed at their lowermost extremities into footlike portions as shown in FIG. 4. Each of the webbed receptacles 33 is fixed to the base 23, in a position corresponding to the position of its associated bifurcated latching member 25, by means of a pair of screws 35, and each is provided with an upright webbed extension 37 that forms an arcuate slot 39 into which the transverse rod 27 of its associated bifurcated member is insertably introduced when the cover 21 is lowered into its latched position on the base 23, such arcuate slot 39 terminating in an offset recess 41 which lockably retains its associated transverse rod 27 when the cover 21 is latched in place. The transverse rods 27 are conveniently insertable into the arcuate slots 39 and into the offset recesses 41 of their associated webbed receptacles 33 by tilting the cover 21 in a manner illustrated in FIG. 4, and by lowering the cover 21 in a counterclockwise tilting motion.

As illustrated in FIGS. 7 and 8, the rear latching means of the present invention is comprised of a pair of spaced-apart foot members 43 attached to a pair of depending projections 45 interiorly disposed in contiguous relationship to the rear side of the cover 21, and a pair of rotatable cam hooks 51 and 53 associated with a slide member 69, the cam hooks 51 and 53 and the slide member 69 being interiorly and operably mounted on the rear side of the base 23 by means of a pair of double-shouldered screws 55. Each of the foot members 43 comprises an inwardly directed stud 47. The cam hook 51 is rotatably mounted in proximity to the right side of the base 23, in cooperating relationship with the rightmost foot member 43 of the cover 21, and the cam hook 53 is rotatably mounted in proximity to the left side of the base 23, in cooperating relationship with the leftmost foot member 43.

The slide member 69 is translatably mounted on the pair of double-shouldered screws 55 by means of a pair of slots 70 formed in the outermost extremities thereof. The slide member 69 is provided on its leftmost extremity with an upwardly directed projection 71 having a slot 75 formed-therein, and provided on its rightmost extremity with a depending extension 73 which also has a slot 75, said slots of the projection 71 and extension 73 hearing an equivalent but oppositely directed angular relationship to a vertical plane intermediate thereto. Each of the rotatable cam hooks 51 and 53 is provided with a-stud 63 fixed to the outer side surface thereof, such studs being engageably associated with the slots 75 of the extension 73 and the projection 71, respectively. Each of the cam books 51 and 53 is also provided with a hook portion 57, a cam segment 59, and an anchor stud 67 fixed to the inner side surface thereof. The book portions 57 and the cam segments 59 of the rotatable cam hooks 51 and 53 are separated by an arcuate slot 61 which terminates in an offset recess 62. The anchor studs 67 are connected by a spring 65 the function of which is hereinafter described in greater detail. The arrangement of the rotatable cam books 51 and 53 and the slide member 69 is such that a leftward translation of the slide member 69 (as viewed in F IG. 7) will cause the rightmost cam hook 51 to rotate in a clockwise direction on its double-shouldered mounting screw 55, and cause the leftmost cam hook 53 to rotate in a counterclockwise direction on its respective double-shouldered screw 55, such rotation of the cam hooks 51 and 53 being effectuated by the camming action of the slots 75 of the extension 73 and the projection 71, respectively, on the studs 63 fixed to the respective cam hooks. In like manner the rightward translation of the slide member 69 (from the position illustrated in FIG. 8) will cause the cam hook 51 to rotate in a counterclockwise direction, and the cam hook 53 to rotate in a clockwise direction, as also motivated by the camming action of the slots 75 on the studs 63.

The placement of the anchor studs 67 on the rotatable cam hooks 51 and 53, and the positioning of the spring 65 therebetween, is such that the spring 65 will be positioned above a horizontal plane defined by the double-shouldered screws 55 when the slide member 69 is located in its rightwardly translated position as shown in FIG. 7, and will be positioned below such horizontal plane when the slide member 69 is located in its leftwardly translated position as shown in FIG. 8. This movement of the spring 65 as between its two positions relative to the horizontal plane is accompanied by an expansion of the spring as the anchor studs 67 reach a point of maximum spaced-apart relationship during the oppositely directed rotation of the cam hooks 51 and 53, beyond which point the spring 65 contracts and exerts a motivating force which effectively completes the rotation of the cam hooks 51 and 53 and the translation of the slide member 69.

The slide member 69 is also provided with an aperture 77 and with an ofiset tab 81 as shown in FIGS. 7 and 8. When the slide member 69 is located in its leftward translated position as shown in FIG. 8, the aperture '77 is fully aligned with the aperture 79 formed in the base 23. The aperture 77 is disaligned with the aperture 79 of the base 23 when the slide member 69 is located in its rightward translated position as shown in FIG. 7. The offset tab 81 extends outwardly from the base 23 through a cutout 83 formed therein, the tab 81 being manipulatively accessible from the outside of the machine case as shown in FIG. 2.

When the cover portion 21 of the machine case is lowered into place from the position shown in FIG. 7, the studs 47 of the foot members 43 contact the uppermost radial surfaces of the cam segments 59 of their associated rotatable cam hooks 51 and 53 to exert a camming force against such segments and to thereby initiate an oppositely directed rotation of the cam hooks 51 and 53, the cam hook 51 being rotated in a clockwise direction and the hook 53 being rotated in a counterclockwise direction. This camming action of the studs 47 against the segments 59 is continued, as the studs travel inwardly into the arcuate slots 61, until such time as the spring 65 is expanded by the outwardly and downwardly moving anchor studs 67. The spring 65 is thereby moved below the horizontal plane defined by the double-shouldered screws 55 to exert a continuing rotational force to the cam books 51 and 53, the cam hooks being rotated to their full clockwise and counterclockwise rocked positions, respectively, wherein the offset recesses 62 are lockably engaged with the studs 47 of the foot members 43, as illustrated in FIG. 8. This described clockwise rotation of the cam hook 51 and counterclockwise rotation of the cam hook 53 is accompanied by the leftward translation of the slide member 69 through the camming action of the studs 63 against the walls of the slots 75. As previously described, the leftward translation of the slide member 69 results in the alignment of the aperture 77 formed therein and the aperture 79 formed in the base 23. With the apertures so aligned, the female plug of an electrical supply cord may be passed through the apertures 79 and 77 and connected to the calculating machine.

The studs 47 of the foot members 43 are released from their locked positions in the offset recesses 62 of the cam books 51 and 53, as illustrated in FIG. 8, by manually moving the offset tab 81 in a rightward direction (leftward direction relative to the rear of the case as shown in FIG. 2). This manual movement of the offset tab 81 results in the rightward translation of the slide member 69 (as viewed in FIG. 8), such translation resulting in the counterclockwise rotation of the cam hook S1 and the clockwise rotation of the cam hook 53, as motivated by the camming action of the walls of the slots 75 against the studs 63. The offset recesses 62 and the arcuate slots 61 of the cam hooks are accordingly withdrawn from their blocking positions relative to the studs 47 of the foot members 43. During this rightward translation of the slide member 69, the aperture 77 of the slide member is disaligned with the aperture 79 formed in the base 23, and the spring 65 is raised and expanded by the outwardly and upwardly moving studs 67. At such time as the spring 65 is moved to a position above the horizontal plane defined by the double-shouldered screws 55, the spring 65 is permitted to contract and to exert a continuing rotational force to the cam hooks 51 and 53, such force effectively locating the cam hooks 51 and 53 in their full counterclockwise and clockwise rocked positions, respectively. The cover portion 21 may thus be moved upwardly from the base portion 23, as illustrated in FIG. 7. It is to be observed that the female plug of an electrical supply cord would extend through both the aperture 77 of the slide member 69 and through the aperture 79 of the base 23 when it is connected to the calculating machine. Since the offset tab 81 and the slide member 69 could not be manually translated to'the right (as shown in FIG. 8) when the plug is engaged with the aperture 77, the plug would have to be disconnected from the calculating machine before the cover 21 could be removed.

It can thus be seen that the cover portion 21 may be removed from the base portion 23 by: (1) disconnecting and removing the electrical supply cord from the calculating machine and from the apertures 77 and 79, (2) manually activating the offset tab 81 to the left (as viewed in FIG. 2), and (3) lifting the reannost end of the cover potion 21 (rightmost end as viewed in FIG. 1) from the base portion 23 and rocking the cover portion 21 in a counterclockwise tilting direction.

Replacement of the cover 21 on the base portion 23 may be accomplished by introducing the transverse rods 27 of the bifurcated latching members 25 into the arcuate slots 39 formed in the webbed receptacles 33, with the cover held in a clockwise tilted position as shown in FIG. 4, and by thereafter tiltably lowering the cover member 21 in a counterclockwise direction, such counterclockwise tilting movement resulting in the lockable insertion of the studs 47 of the foot members 43 into the offset recesses 62 of the rotatable cam hooks 51 and 53, as shown in FIGS. 7 and 8.

It can also be seen that the cover 21 cannot be removed from the base portion 23 with the electrical supply cord connected to the calculating machine, and that the electrical supply cord cannot be reconnected to the calculating machine with the cover 21 removed from the base portion.

While the invention has been described with respect to the preferred embodiment thereof, it will be understood that the invention and its various features are capable of changes and variations which are within the spirit and scope of the following claims.

lclaim:

1. A cover-latching device for the case of electrically operated apparatus, said case having a first aperture formed in a base portion thereof through which an electrical supply cord is connectable with said apparatus, said cover-latching device comprising:

a. slidably coupleable first latching means interiorly fixed at single complementary sides of said cover and said base portion, and

b. rockably coupleable second latching means interiorly fixed at complementary single sides of said cover and said base portion opposite said sides comprising said first latching means, said second latching means being latchably responsive to said first latching means and cooperable therewith to lock said cover of said case to said base portion, said second latching means including an apertured slide having a second aperture cooperably associated with said first aperture of said base portion to permit said connection of said supply cord with said electrically operated apparatus when said cover is locked in place by said first and said second latching means, and being also blockingly associated with said first aperture to prevent said connection of said supply cord with said apparatus when said cover is displaced or removed from said base portion.

2. The cover-latching device defined in claim 1 wherein said slidably coupleable first latching means comprises:

a. at least one transverse rod supportably connected to said cover at said single side thereof, and

b. at least one webbed receptacle supportably connected to said base portion at the side thereof complementary to said single side of said cover comprising said transverse rod, said webbed receptacle having an arcuate slot with a terminal offset recess formed therein, said transverse rod supportably connected to said cover being slidably insertable into said arcuate slot of said webbed receptacle and into said tenninal offset recess thereof when said cover is tiltably lowered into place on said base portion, said positioning of said transverse rod in said offset recess being effective to lock said side of said cover to said complementary side of said base portion when said cover is lowered to an untilted position relative to said base portion.

3. The cover-latching device defined in claim 2 wherein said transverse rod of said slidably coupleable first latching means is supported by a bifurcated member interiorly fixed to said cover, said bifurcated member comprising a pair of depending prongs to which said transverse rod is rigidly connected.

4. The cover-latching device defined in claim 3 wherein said slidably coupleable first latching means comprises:

a. a pair of said bifurcated members and said transverse rods interiorly fixed in spaced-apart relationship to said cover, and

b. a pair of said webbed receptacles interiorly fixed in spaced-apart relationship to said base portion, said pair of webbed receptacles being cooperably aligned with said pair of transverse rods.

5. The cover-latching device defined in claim 4 wherein said rockably coupleable second latching means comprises:

a. at least one foot member interiorly fixed to said cover at said side opposite said single side comprising said bifurcated member and said transverse rod, said foot member having a stud fixed to the side surface of the free end extremity thereof,

b. at least one rotatable cam hook associated with said foot member and with said apertured slide, said cam hook being interiorly and rotatably mounted to said base portion of the side thereof complementary to said side of said cover comprising said foot member, said mounting of said cam hook being effectuated by means of a first shouldered screw, said apertured slide being latitudinally and translatably mounted in cooperating relationship with said rotatable cam hook by means of said first shouldered screw and a second shouldered screw fixed to said base portion, and

c. a spring associated with said rotatable cam hook and mounted in contiguous and substantially parallel relationship with said translatably mounted apertured slide.

6. The coverlatching device defined in claim 5 wherein said apertured slide additionally comprises:

a. a first and a second slot associated with said first and said second shouldered screws,

b. at least a third slot associated with said rotatable cam hook, and

c. an offset tab extending outwardly through a cutout formed in said base portion.

7. The cover-latching device defined in claim 6 wherein said rotatably mounted cam hook is provided with:

a. an outwardly directed stud engageably associated with said third slot of said apertured slide,

b. an inwardly directed anchor stud to which one end of said spring is connected,

c. a hook portion, and

d. a cam segment contactably associated with said inwardly directed stud of said foot member, said hook portion and said cam segment forming an arcuate slot therebetween in which said stud of said foot member reciprocally travels during said rotation of said cam hook in a first and a second direction, said arcuate slot terminating in an offset recess which lockably houses said stud of said foot member when said cam hook has been fully rotated in said first direction.

8. The cover-latching device defined in claim 7 wherein said rockably coupleable second latching means comprises:

a. a pair of said foot members and said associated studs interiorly fixed to said cover in spaced-apart relationship,

b. an apertured slide comprising said third slot and a fourth slot, and

c. a pair of said rotatable cam hooks interiorly mounted in spaced-apart relationship by means of said first and said second shouldered screws, each of said cam hooks comprising a hook portion and a cam segment forming an arcuate slot having a terminal offset recess, and comprising als'oan anchor stud to which one end of said spring is connected and an outwardly directed stud engageably associated with either said third or said fourth slot of said apertured slide, said studs of said pair of foot members being lockably housed in said offset recesses of said arcuate slots of said pair of cam hooks when said cam hooks have been fully rotated in their said first direction, said first direction rotation of said cam hooks being oppositely directed.

9. The cover-latching device defined in claim 8 wherein said slidably' coupleable first latching means and said rockably coupleable second latching means are so disposed relative to opposite complementary sides of said cover and said base portion of said case that the lowering of the tilted cover to activate said first latching means results in said slidable entry of said transverse rods into their said locked position in said offset recesses of said webbed receptacles, and that the tiltable lowering of said cover into place on said base portion to activate said second latching means results in said first direction rotation of said pair of cam hooks as motivated by the camming action of said studs of said pair of foot members against said cam segments thereof, said first direction rotation of said cam hooks being effective through said anchor studs to lower said spring from a position above a horizontal plane defined by said first and said second shouldered screws to a position therebelow, and effective also through said outwardly directed studs of said cam hooks and said third and said fourth slots of said apertured slide to translate said apertured slide in such manner as to align said second aperture thereof with said first aperture of said base portion, said first direction rotation of said cam hooks being completed by the contraction of said spring at such time during said lowering movement as it passes said horizontal plane, said completion of said first direction rotation of said cam hooks being effective to position said of?- set recesses thereof in locking relationship with said studs of said pair of foot members.

10. The cover-latching device defined in claim 8 wherein said second latching means is uncoupleably responsive to the manual manipulation of said offset tab extending through said cutout formed in said base portion, said manipulation resulting in said second direction rotation of said cam hooks by means of the camming action of the walls of said third and said fourth slots of said apertured slide against said outwardly directed studs of said cam hooks, said second direction rotation of said cam hooks being effective to raise said spring from a position below said horizontal plane to a position thereabove, said second direction rotation of said cam hooks being com hated by the contraction of saids ring at such time during sai rising movement as it passes sat horizontal plane,

said completion of said second direction rotation being effective to release said studs of said pair of foot members from said offset recesses and said arcuate slots formed in said pair of cam hooks, said manual manipulation of said offset tab of said apertured slide resulting also in a disaligned relationship between said second aperture of said slide and said first aperture of said base portion, said disaligned relationship effectively blocking said connection of said electrical supply cord with said electrically operated apparatus.

111. The cover-latching device defined in claim 10 wherein said manual manipulation of said offset tab is prevented by the presence of the tenninal end of said electrical supply cord in said second aperture of said apertured slide and in said first aperture of said base portion of said case. 

1. A cover-latching device for the case of electrically operated apparatus, said case having a first aperture formed in a base portion thereof through which an electrical supply cord is connectable with said apparatus, said cover-latching device comprising: a. slidably coupleable first latching means interiorly fixed at single complementary sides of said cover and said base portion, and b. rockably coupleable second latching means interiorly fixed at complementary single sides of said cover and said base portion opposite said sides comprising said first latching means, said second latching means being latchably responsive to said first latching means and cooperable therewith to lock said cover of said case to said base portion, said second latching means including an apertured slide having a second aperture cooperably associated with said first aperture of said base portion to permit said connection of said supply cord with said electrically operated apparatus when said cover is locked in place by said first and said second latching means, and being also blockingly associated with said first aperture to prevent said connection of said supply cord with said apparatus when said cover is displaced or removed from said base portion.
 2. The cover-latching device defined in claim 1 wherein said slidably coupleable first latching means comprises: a. at least one transverse rod supportably connected to said cover at said single side thereof, and b. at least one webbed receptacle supportably connected to said base portion at the side thereof complementary to said single side of said cover comprising said transverse rod, said webbed receptacle having an arcuate slot with a terminal offset recess formed therein, said transverse rod supportably connected to said cover being slidably insertable into said arcuate slot of said webbed receptacle and into said terminal offset recess thereof when said cover is tiltably lowered into place on said base portion, said positioning of said transverse rod in said offset recess being effective to lock said side of said cover to said complementary side of said base portion when said cover is lowered to an untilted position relative to said base portion.
 3. The cover-latching device defined in claim 2 wherein said transverse rod of said slidably coupleable first latching means is supported by a bifurcated member interiorly fixed to said cover, said bifurcated member comprising a pair of depending prongs to which said transverse rod is rigidly connected.
 4. The cover-latching device defined in claim 3 wherein said slidably coupleable first latching means comprises: a. a pair of said bifurcated members and said transverse rods interiorly fixed in spaced-apart relationshIp to said cover, and b. a pair of said webbed receptacles interiorly fixed in spaced-apart relationship to said base portion, said pair of webbed receptacles being cooperably aligned with said pair of transverse rods.
 5. The cover-latching device defined in claim 4 wherein said rockably coupleable second latching means comprises: a. at least one foot member interiorly fixed to said cover at said side opposite said single side comprising said bifurcated member and said transverse rod, said foot member having a stud fixed to the side surface of the free end extremity thereof, b. at least one rotatable cam hook associated with said foot member and with said apertured slide, said cam hook being interiorly and rotatably mounted to said base portion of the side thereof complementary to said side of said cover comprising said foot member, said mounting of said cam hook being effectuated by means of a first shouldered screw, said apertured slide being latitudinally and translatably mounted in cooperating relationship with said rotatable cam hook by means of said first shouldered screw and a second shouldered screw fixed to said base portion, and c. a spring associated with said rotatable cam hook and mounted in contiguous and substantially parallel relationship with said translatably mounted apertured slide.
 6. The cover-latching device defined in claim 5 wherein said apertured slide additionally comprises: a. a first and a second slot associated with said first and said second shouldered screws, b. at least a third slot associated with said rotatable cam hook, and c. an offset tab extending outwardly through a cutout formed in said base portion.
 7. The cover-latching device defined in claim 6 wherein said rotatably mounted cam hook is provided with: a. an outwardly directed stud engageably associated with said third slot of said apertured slide, b. an inwardly directed anchor stud to which one end of said spring is connected, c. a hook portion, and d. a cam segment contactably associated with said inwardly directed stud of said foot member, said hook portion and said cam segment forming an arcuate slot therebetween in which said stud of said foot member reciprocally travels during said rotation of said cam hook in a first and a second direction, said arcuate slot terminating in an offset recess which lockably houses said stud of said foot member when said cam hook has been fully rotated in said first direction.
 8. The cover-latching device defined in claim 7 wherein said rockably coupleable second latching means comprises: a. a pair of said foot members and said associated studs interiorly fixed to said cover in spaced-apart relationship, b. an apertured slide comprising said third slot and a fourth slot, and c. a pair of said rotatable cam hooks interiorly mounted in spaced-apart relationship by means of said first and said second shouldered screws, each of said cam hooks comprising a hook portion and a cam segment forming an arcuate slot having a terminal offset recess, and comprising also an anchor stud to which one end of said spring is connected and an outwardly directed stud engageably associated with either said third or said fourth slot of said apertured slide, said studs of said pair of foot members being lockably housed in said offset recesses of said arcuate slots of said pair of cam hooks when said cam hooks have been fully rotated in their said first direction, said first direction rotation of said cam hooks being oppositely directed.
 9. The cover-latching device defined in claim 8 wherein said slidably coupleable first latching means and said rockably coupleable second latching means are so disposed relative to opposite complementary sides of said cover and said base portion of said case that the lowering of the tilted cover to activate said first latching means results in said slidable entry of said transverse rods into their said locked position in said offset recesses of saId webbed receptacles, and that the tiltable lowering of said cover into place on said base portion to activate said second latching means results in said first direction rotation of said pair of cam hooks as motivated by the camming action of said studs of said pair of foot members against said cam segments thereof, said first direction rotation of said cam hooks being effective through said anchor studs to lower said spring from a position above a horizontal plane defined by said first and said second shouldered screws to a position therebelow, and effective also through said outwardly directed studs of said cam hooks and said third and said fourth slots of said apertured slide to translate said apertured slide in such manner as to align said second aperture thereof with said first aperture of said base portion, said first direction rotation of said cam hooks being completed by the contraction of said spring at such time during said lowering movement as it passes said horizontal plane, said completion of said first direction rotation of said cam hooks being effective to position said offset recesses thereof in locking relationship with said studs of said pair of foot members.
 10. The cover-latching device defined in claim 8 wherein said second latching means is uncoupleably responsive to the manual manipulation of said offset tab extending through said cutout formed in said base portion, said manipulation resulting in said second direction rotation of said cam hooks by means of the camming action of the walls of said third and said fourth slots of said apertured slide against said outwardly directed studs of said cam hooks, said second direction rotation of said cam hooks being effective to raise said spring from a position below said horizontal plane to a position thereabove, said second direction rotation of said cam hooks being completed by the contraction of said spring at such time during said rising movement as it passes said horizontal plane, said completion of said second direction rotation being effective to release said studs of said pair of foot members from said offset recesses and said arcuate slots formed in said pair of cam hooks, said manual manipulation of said offset tab of said apertured slide resulting also in a disaligned relationship between said second aperture of said slide and said first aperture of said base portion, said disaligned relationship effectively blocking said connection of said electrical supply cord with said electrically operated apparatus.
 11. The cover-latching device defined in claim 10 wherein said manual manipulation of said offset tab is prevented by the presence of the terminal end of said electrical supply cord in said second aperture of said apertured slide and in said first aperture of said base portion of said case. 